Systemic Amlexanox, a TBK1/IKKε Inhibitor, Decreases IFN-γ-mediated Phosphorylation of STAT1-Blocking Atherogenic Signaling and Preventing Intimal Hyperplasia After Carotid Artery Balloon Angioplasty

Peripheral arterial disease affects >230 million people worldwide and causes significant morbidity. Venous interposition bypass grafts or endovascular balloon angioplasty with stenting are the cornerstone of current revascularization procedures. Unfortunately, 30% to 50% of venous interposition bypass grafts fail within 5 years, and 20% to 30% of angioplasties fail within one year due to intimal hyperplasia (IH). Given the implication of atherogenic IFN-γ signaling in driving IH, we investigated the impact of Amlexanox, a small molecule inhibitor of TBK1/IKKε and potential modulator of IFN-γ signaling, on IH in a rat model of carotid artery stenosis after balloon angioplasty. Sprague-Dawley rats were pretreated with intraperitoneal Amlexanox (100 mg/kg/day) or control dimethyl-sulfoxide (DMSO) for 7 days prior and up to 14 days after (at sacrifice) balloon angioplasty. IH was quantified by intima:media ratio on hematoxylin and eosin-stained vessel sections, and nuclear phospho-STAT1, a biomarker of IFN-γ signaling, was evaluated by immunohistochemistry and quantified by image J software. Systemic Amlexanox significantly reduced the intima:media ratio 14 days after carotid balloon angioplasty. I/M ratio reached 0.43 ± 0.54 vs1.38 ± 0.71 in Amlexanox vs DMSO-treated rats (P < .05; n = 7-8) (Fig. 1). The beneficial effect of Amlexanox correlated with a significantly lower number of nuclear phospho-STAT1 positive cells in the carotid artery intima and media 14 days after angioplasty (243 ± 214 vs 1005 ± 552 positive nuclei in Amlexanox vs DMSO; P < .05, n = 4) (Fig 2). Importantly, Amlexanox treatment was well-tolerated and did not induce any liver, pancreatic, or renal toxicity. This is the first report showing that systemic Amlexanox inhibits atherogenic IFN-γ signaling, significantly limiting IH following carotid artery balloon angioplasty. These results posit Amlexanox as a novel, safe and promising anti-atherogenic treatment to minimize pathologic vascular remodeling post-angioplasty. Future research is geared towards dose optimization, and exploring feasibility/effectiveness of local (balloons/stents) vs systemic delivery of Amlexanox.Fig 2Representative images of phospho-STAT1 immunostaining (brown nuclei arrow) in Amlexanox vs DMSO-treated rats in carotid artery sections 14 days after balloon angioplasty. Original magnification ×400. Histograms on the right delineate mean ± standard error of the mean of PSTAT1-positive nuclei in intima + media per vessel section (n = 4; P < .05).View Large Image Figure ViewerDownload Hi-res image Download (PPT)